OBJECTIVES To identify factors affecting the sex ratio at birth. DESIGN Cross-sectional study. SETTING Obstetric department of a public hospital in Hong Kong. PARTICIPANTS All pregnant women delivered between 2001 and 2010. MAIN OUTCOME MEASURES Sex ratio at birth versus women's eligibility status, age, parity, number of miscarriages or terminations of pregnancy, and number of fetuses w...

Given a finite family F of convex sets in R, we say that F has the (p, q)r property if for any p convex sets in F there are at least r q-tuples that have non empty intersection. The piercing number of F is the minimum number of points we need to intersect all the sets in F . In this paper we willl find some bounds for the piercing number of families of convex sets with (p, q)r properties.

Myers conjectured that for every integer s there exists a positive constant C such that for all integers t every graph of average degree at least Ct contains a Ks,t minor. We prove the following stronger result: for every 0 < ε < 10−16 there exists a number t0 = t0(ε) such that for all integers t ≥ t0 and s ≤ εt/ log t every graph of average degree at least (1 + ε)t contains a Ks,t minor. The b...

We revisit the construction of high noise, almost optimal rate list decodable code of Guruswami [1]. Guruswami showed that if one can explicitly construct optimal extractors then one can build an explicit (1− 2, O( 1 2 )) list decodable codes of rate Ω( 2 log 1 2 ) and alphabet size 2 1 2 ·log 1 2 . We show that if one replaces the expander component in the construction with an unbalanced dispe...

Low coherence interference microscopy (LCIM) provides high spatial phase sensitivity, i.e., speckle free and coherent noise quantitative images of the test specimens. Due to low temporal (TC) length light source, LCIM requires precise adjustment optical path difference (OPD) between object reference arm, which is only a few micrometers. Consequently, previously demonstrated systems are implemen...